Adaptive charge balanced edge termination

Abstract

In one embodiment, a semiconductor device can include a substrate including a first type dopant. The semiconductor device can also include an epitaxial layer located above the substrate and including a lower concentration of the first type dopant than the substrate. In addition, the semiconductor device can include a junction extension region located within the epitaxial layer and including a second type dopant. Furthermore, the semiconductor device can include a set of field rings in physical contact with the junction extension region and including a higher concentration of the second type dopant than the junction extension region. Moreover, the semiconductor device can include an edge termination structure in physical contact with the set of field rings.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. patent application Ser. No. 13/484,114, now U.S. Pat. No. 9,842,911, entitled “Adaptive Charge Balanced Edge Termination”, by Naveen Tipirneni et al., filed May 30, 2012, which is hereby incorporated by reference.

BACKGROUND

There are different types of edge termination structures used to increase the breakdown voltage of P-N junctions in semiconductor devices such as diodes, metal-oxide semiconductor field-effect transistor (MOSFET) devices, insulated-gate bipolar transistor (IGBT) devices, bipolar junction transistor (BJT) devices, and the like. Various edge termination structures have been developed including, for example, field plate structures, field limiting rings with or without field plates, junction termination extension (JTE) and its variants. However, it is desirable to develop an edge termination structure utilizing as small a width as possible to achieve ideal planar breakdown voltages on given P-N junctions.

SUMMARY

Various embodiments in accordance with the invention provide efficient, manufacturable, and robust edge termination techniques utilizing a smaller width that are able to achieve ideal planar breakdown voltages on given P-N junctions.

In one embodiment, a semiconductor device can include a substrate including a first type dopant. The semiconductor device can also include an epitaxial layer located above the substrate and including a lower concentration of the first type dopant than the substrate. In addition, the semiconductor device can include a junction extension region located within the epitaxial layer and including a second type dopant. Furthermore, the semiconductor device can include a set of isolated narrow and shallow field rings in physical contact with the junction extension region and including a higher concentration of the second type dopant than the junction extension region. Moreover, the semiconductor device can include an edge termination structure in physical contact with the set of field rings.

In another embodiment, a method can include generating a junction extension region within an upper surface of an epitaxial layer of a semiconductor device. The epitaxial layer can include a first type dopant and the junction extension region can include a second type dopant. Furthermore, the method can include generating a set of isolated narrow and shallow field rings in physical contact with the junction extension region and including a higher concentration of the second type dopant than the junction extension region. Additionally, the method can include generating an edge termination structure in physical contact with the set of field rings.

In yet another embodiment, a metal oxide semiconductor field effect transistor (MOSFET) device can include a substrate including a first type dopant. Also, the MOSFET device can include an epitaxial layer located above the substrate and including a lower concentration of the first type dopant than the substrate. Moreover, the MOSFET device can include a junction extension region located within the epitaxial layer and including a second type dopant. Additionally, the MOSFET device can include a set of isolated narrow and shallow field rings in physical contact with the junction extension region and including a higher concentration of the second type dopant than the junction extension region. Furthermore, the MOSFET device can include an edge termination structure in physical contact with the set of field rings.

While particular embodiments in accordance with the invention have been specifically described within this Summary, it is noted that the invention and the claimed subject matter are not limited in any way by these embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Within the accompanying drawings, various embodiments in accordance with the invention are illustrated by way of example and not by way of limitation. It is noted that like reference numerals denote similar elements throughout the drawings.

FIG. 1 is a side sectional view of an adaptive charge balanced edge termination of a semiconductor device in accordance with various embodiments of the invention.

FIG. 2 is side sectional view of a conventional single zone junction termination extension (JTE).

FIG. 3 is a graph comparing breakdown voltage sensitivity to charge variation in a conventional JTE and an adaptive charge balanced edge termination in accordance with various embodiments of the invention.

FIG. 4 illustrates the dependence of breakdown voltage on a junction extension charge for an adaptive charge balanced edge termination in accordance with various embodiments of the invention.

FIG. 5 illustrates the dependence of breakdown voltage on a junction extension charge for a single zone junction termination extension.

FIGS. 6-10 illustrate a process for fabricating an adaptive charge balanced edge termination of a semiconductor device in accordance with various embodiments of the invention.

FIG. 11 is flow diagram of a method in accordance with various embodiments of the invention.

The drawings referred to in this description should not be understood as being drawn to scale except if specifically noted.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments in accordance with the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with various embodiments, it will be understood that these various embodiments are not intended to limit the invention. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the scope of the invention as construed according to the Claims. Furthermore, in the following detailed description of various embodiments in accordance with the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be evident to one of ordinary skill in the art that the invention may be practiced without these specific details or with equivalents thereof. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the invention.

Some portions of the detailed descriptions that follow are presented in terms of procedures, logic blocks, processing, and other symbolic representations of operations for fabricating semiconductor devices. These descriptions and representations are the means used by those skilled in the art of semiconductor device fabrication to most effectively convey the substance of their work to others skilled in the art. In the present application, a procedure, logic block, process, or the like, is conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present application, discussions utilizing terms such as “generating,” “creating,” “forming,” “performing,” “producing,” “depositing,” “etching”, “defining”, “removing” or the like, refer to actions and processes of semiconductor device fabrication.

The figures are not drawn to scale, and only portions of the structures, as well as the various layers that form those structures, may be shown in the figures. Furthermore, fabrication processes and steps may be performed along with the processes and steps discussed herein; that is, there may be a number of process steps before, in between and/or after the steps shown and described herein. Importantly, embodiments in accordance with the invention can be implemented in conjunction with these other (perhaps conventional) processes and steps without significantly perturbing them. Generally speaking, embodiments in accordance with the invention can replace portions of a conventional process without significantly affecting peripheral processes and steps.

As used herein, the letter “N” refers to an N-type dopant and the letter “P” refers to a P-type dopant. A plus sign “+” or a minus sign “−” is used to represent, respectively, a relatively high or relatively low concentration of the dopant.

The term “channel” is used herein in the accepted manner. That is, current moves within a FET in a channel, from the source connection to the drain connection. A channel can be made of either n-type or p-type semiconductor material; accordingly, a FET is specified as either an n-channel or p-channel device. Note that some of the figures are discussed in the context of an n-channel device, specifically an n-channel MOSFET. However, embodiments in accordance with the invention are not so limited. The discussion of the figures can be readily mapped to a p-channel device by substituting n-type dopant and materials for corresponding p-type dopant and materials, and vice versa.

FIG. 1 is a side sectional view of an adaptive charge balanced edge termination area 106 of a semiconductor device 100 in accordance with various embodiments of the invention. With the present embodiment, the adaptive charge balanced edge termination area 106 includes the main P-N junction of the semiconductor device 100 being terminated along with a P type junction extension region 110 at the surface of the semiconductor device 100. In an embodiment, the junction extension region 110 includes laterally varying dopant wherein the doping is more intense closer to source metal 108 and gradually decreases in doping intensity further away from the source metal 108. Within one embodiment, the junction extension region 110 can include highly doped P field rings 114 which are used to form an ohmic contact between the silicon and multiple field plates 112. In an embodiment, the field rings 114 can be implemented as isolated, narrow, and shallow field rings 114. In one embodiment, the semiconductor device 100 can include an N+ substrate 102, an N− doped epitaxial region 104, source metal 108, and the adaptive charge balanced edge termination area 106. In an embodiment, the junction extension region 110 is terminated by a polysilicon and metal field plate 118, which further extends the breakdown voltage due to the traditional field plate action (e.g., depletion from the MOS section consisting of the field plate and the isolation dielectric and the silicon epitaxial region). In an embodiment, the thickness of the isolation dielectric is chosen according to the differential breakdown voltage between the drain potential and the field plate potential. It is pointed out that the polysilicon and metal field plate 118 of the present embodiment includes a polysilicon field plate 116. Note that in an embodiment, the N+ substrate 102 and the N− doped epitaxial region 104 can collectively be referred to as a substrate, but are not limited to such. A channel stop region is described in detail later (e.g., FIG. 10) and is not shown here.

Within the present embodiment, the junction extension region 110 excluding the specially confined highly P type doped ohmic field rings 114 can include a total charge per unit area which is about 10%-70% of the charge value at which conventional JTE (e.g., within FIG. 2) or JTE variants achieves highest breakdown voltage or charge balance conditions. It is noted that in the semiconductor device 100, under reverse bias conditions, the charge in junction extension region 110 excluding ohmic field rings 114 depletes at a certain cathode voltage which depends on the depleted charge in the region and at a voltage that is small compared to the breakdown voltage of the P-N junction of the semiconductor device 100. Once the junction extension region 110 is depleted, the field plates 112 connected to the silicon through ohmic field rings 114 float to different voltages depending on the potential distribution in the depleted P type junction extension region 110. Note that the field plates 112 located closer to the cathode potential side at the surface float to a higher potential. In addition, the field plates 112 located closer to the anode potential side at the surface float to a lower potential. The field plates 112 which float to negative potentials with respect to cathode potential aid in depleting the N type silicon and hence mitigating the electric fields experienced by the main P-N junction and its extension area 110.

Within FIG. 1, the P+ field rings 114 in an embodiment are able to force another distribution of the potential in addition to the potential distribution that occurs without the P+ field rings 114. Furthermore, in one embodiment, the adaptive charge balanced edge termination area 106 is adapting the potential drop in silicon within its field plates structures 112 located on the top of the silicon. Specifically, each of the field plates 112 includes metal that has a constant potential. Additionally, each of these metals of the field plates 112 has a similar potential that can force an electric field on top of the silicon of the semiconductor device 100.

It is pointed out that in an embodiment the adaptive charge balanced edge termination area 106 can be very efficient in terms of the space (or area) used to achieve breakdown voltages close to ideal value. For example in one embodiment, by utilizing the adaptive charge balanced edge termination area 106, the P-N junction semiconductor device 100 when designed for 660 volts (V) operation can be effectively terminated using less than 110 microns (or micrometers) of silicon surface of the semiconductor device 100. In addition, the adaptive charge balanced edge termination area 106 has a wide margin for manufacturing variations when compared with a conventional junction termination extension structure (e.g., FIG. 2).

Within FIG. 1, note that the semiconductor device 100 can be implemented in a wide variety of ways. For example, in various embodiments, the semiconductor 100 can be implemented as, but is not limited to, a diode, a metal-oxide semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT), a bipolar junction transistor (BJT), and the like. In addition, in various embodiments, the adaptive charge balanced edge termination area 106 of the semiconductor device 100 can include a greater or lesser number of field plates than the field plates 112 shown within FIG. 1. Furthermore, in one embodiment, a passivation layer (not shown) can be deposited above the source metal 108, the field plate structures 112, and any other structures and upper surfaces of the semiconductor device 100. Moreover, in an embodiment, a layer of polyimide (not shown) can be deposited over the source metal 108, the field plate structures 112, and any other structures and upper surfaces of the semiconductor device 100. In an embodiment, the junction extension region 110 can be implemented as P− junction extension region 110, but is not limited to such. In one embodiment, the doping concentration of the P− junction termination extension region 110 can be substantially lower than that of a conventional single zone JTE (e.g., 206 of FIG. 2) for silicon. For example, in an embodiment, the doping concentration of the P− junction extension region 110 can be, but is not limited to, of the order of approximately 1×10¹¹/cm³ while the doping concentration of a conventional single zone JTE is 1×10¹²/cm³ for silicon.

It is pointed out that FIG. 1 includes both an X-axis and Y-axis that illustrate the cross sectional size of the semiconductor device 100. Specifically, the X-axis of FIG. 1 includes a micron (or micrometer) scale while the Y-axis includes a micron (or micrometer) scale.

Note that the semiconductor device 100 may not include all of the elements illustrated by FIG. 1. Additionally, the semiconductor device 100 can be implemented to include one or more elements not illustrated by FIG. 1. It is pointed out that the semiconductor device 100 can be utilized or implemented in any manner similar to that described herein, but is not limited to such.

FIG. 2 is side sectional view of a conventional single zone junction termination extension (JTE) 206 of a semiconductor device 200. It is pointed out that the single zone junction termination extension 202 is included herein to illustrate the advantages of various embodiments in accordance with the invention. The semiconductor device 200 includes a substrate 202, an epitaxial region 204, the junction termination extension 206, and a source metal 108. It is noted that the junction termination extension 206 is fabricated within the epitaxial region 204 and includes laterally varying doping. Specifically, the doping of the junction termination extension 206 is more intense closer to the source metal 208 and gradually decreases in doping intensity further away from the source metal 108.

FIG. 3 is a graph 300 illustrating a comparison of breakdown voltage sensitivity to charge variation in the junction extension region 110 of the adaptive charge balanced edge termination structure 106 in accordance with an embodiment of the invention and the conventional junction termination extension 206. It is pointed out that the Y-axis of the graph 300 represents the breakdown voltage (V) while the X-axis of the graph 300 represents the extension charge variation by percent (%). Furthermore, curve 302 of the graph 300 represents the breakdown voltage sensitivity to charge variation in the junction extension region 110 of the adaptive charge balanced edge termination structure 106. In addition, curve 304 of the graph 300 represents the breakdown voltage sensitivity to charge variation in the conventional junction termination extension 206.

Within graph 300, it is pointed out that the curve 302 representing the adaptive charge balanced edge termination structure 106 has a much smoother curve than the curve 304 representing the conventional junction termination extension 206. Moreover, note that the curve 302 does not include the sharp drop exhibited by the curve 304 from zero to approximately 14% charge variation. Therefore, the adaptive charge balanced edge termination structure 106 produces better breakdown voltage sensitivity to charge variation.

FIGS. 4 and 5 will be described and compared to demonstrate that the adaptive charge balanced edge termination structure 106 in accordance with an embodiment of the invention performs better than the conventional single zone junction termination extension 206.

FIG. 4 is a graph 400 illustrating the dependence of breakdown voltage on a junction extension charge for an adaptive charge balanced edge termination structure (e.g., 106) in accordance with various embodiments of the invention. Note that the Y-axis of the graph 400 represents the breakdown voltage (V) while the X-axis of the graph 400 represents the extension charge (/cm²). Additionally, curve 402 of the graph 400 represents the dependence of breakdown voltage on a junction extension charge for the adaptive charge balanced edge termination structure 106.

FIG. 5 is a graph 500 illustrating the dependence of breakdown voltage on a junction extension charge for a conventional single zone junction termination extension (e.g., 206). It is noted that the Y-axis of the graph 500 represents the breakdown voltage (V) while the X-axis of the graph 500 represents the extension charge (/cm²). Furthermore, curve 502 of the graph 500 represents the dependence of breakdown voltage on a junction extension charge for the conventional single zone junction termination extension 206.

Note that the adaptive charge balanced edge termination curve 402 of the graph 400 is a flatter curve than the junction termination extension curve 502 of the graph 500. Therefore, the adaptive charge balanced edge termination structure 106 performs better than the conventional single zone junction termination extension 206. Moreover, it is noted that the lowest extension charge value shown within the graph 400 is an order of magnitude less than the lowest extension charge value shown with the graph 500. As such, the adaptive charge balanced edge termination structure 106 performs better than the conventional single zone junction termination extension 206.

FIGS. 6-10 illustrate a process for fabricating an adaptive charge balanced edge termination of a semiconductor device in accordance with various embodiments of the invention. In one embodiment, the semiconductor device of FIG. 6-10 can include, but is not limited to, a 600 V MOSFET with an adaptive charge balanced edge termination.

FIG. 6 illustrates a side sectional view of an extension ring mask or junction extension region mask 606 in accordance with an embodiment of the invention deposited (or located) on an N− doped epitaxial layer 604, which is formed above an N+ substrate 602. It is noted that in one embodiment, the N+ substrate 602 and the N− doped epitaxial layer 604 can collectively be referred to as a substrate, but are not limited to such.

More specifically, in an embodiment, the junction extension mask 606 can include a larger opening 608 for forming a P type tub region within the N− doped epitaxial layer 604. In addition, the junction extension mask 606 can include a grated mask region 610 which has openings designed so that the desired amount of doped charge is incorporated within the N− doped epitaxial layer 604 to form a P junction extension region for termination using a single high doped boron implantation 612, but is not limited to such. It is pointed out that wherever there are openings within the junction extension mask 606, the boron 612 is able to pass through the openings and into the N− doped epitaxial layer 604. Furthermore, the openings of the grated mask region 610 are designed in such a manner that once the boron 612 is incorporated in the N− doped epitaxial layer 604, the boron 612 will eventually overlap after a thermal drive-in. Additionally, in an embodiment, the openings of the grated mask region 610 are designed to form the P junction extension region for termination having laterally varying dopant wherein the doping is more intense closer to the larger opening 608 and gradually decreases in doping intensity further away from the larger opening 608. In one embodiment, the openings of the grated mask region 610 are larger closer to the larger opening 608 and gradually get smaller further away from the larger opening 608.

After the implantation of boron 612 within the N− doped epitaxial layer 604, FIG. 7 illustrates a thermal charge drive-in of boron 612 within the N− doped epitaxial layer 604 in accordance with various embodiments of the invention. In this manner, a P-tub 702 and a P junction termination extension region 704 are fabricated or formed within the N− doped epitaxial layer 604. It is pointed out that the thermal charge drive-in causes the implanted boron 612 to diffuse and overlap within the N− doped epitaxial layer 604. In addition, after the thermal drive-in process, FIG. 7 illustrates that a field oxide 706 can be grown or deposited onto the N− doped epitaxial layer 604 in accordance with various embodiments of the invention. In an embodiment, the junction extension region 704 can be implemented as P− junction extension region 704, but is not limited to such. In one embodiment, the junction extension region 704 includes laterally varying dopant wherein the doping is more intense closer to the P-tub 702 and gradually decreases in doping intensity further away from the P-tub 702.

After fabricating the field oxide 706, FIG. 8 illustrates that an active mask layer can be utilized to etch off portions of the field oxide 706 thereby exposing the N− doped epitaxial layer 604. At that point, a gate oxide 802 can be grown on or above the top surfaces of the etched field oxide 706 and the N− doped epitaxial layer 604. After which, polysilicon 804 can be deposited on or above the top surfaces of the etched field oxide 706 and the N− doped epitaxial layer 604. Next, a mask can be utilized to etch or pattern away portions of polysilicon 804 resulting in the definition of a gate region 806, a gate runner 808, and a polysilicon field plate 810. It is pointed out that within FIG. 8, an active region 812 of the semiconductor device is on the left side of a vertical dash line while a termination region 814 of the semiconductor device is on the right side of the vertical dash line.

FIG. 9 illustrates body implant within the N− doped epitaxial layer 604, a thermal drive-in, followed by source N+ arsenic and shallow P+ implant resulting in P body 902 in accordance with various embodiments of the invention. Next, a deposition of an interlayer dielectric 904 can be deposited on or over the gate oxide 802 (not shown), the gate runner polysilicon 808, the polysilicon field plate 810, the polysilicon 804, and other upper surfaces of the semiconductor device of FIG. 9.

FIG. 10 illustrates a contact mask can be utilized to contact etch regions (or cavities or holes or trenches) 1012 that extend through the interlayer dielectric 904, the field oxide 706, and into the P junction extension region 704. Next, a shallow boron implant 1006, but not limited to, P+ doped polysilicon (or boron doped polysilicon) can be performed into the P junction extension region 704 at the bottom of each contact cavity 1012. Note that these implantations can be referred to as field rings 1006, which may be isolated, narrow, and shallow. After which, a layer of metal 1002 can be deposited above or over the semiconductor device 1000 and into the contact cavities 1012. Next, the metal 1002 can be etched to fabricate and make independent the source metal 1004, the gate runner 806, field plate structures 1008, and a metal and polysilicon field plate structure 1014. In this manner, the field plate structures 1008 and the metal and polysilicon field plate structure 1014 are in ohmic contact with the P junction extension region 704, but are not limited to such. For example, in one embodiment, the field plate structures 1008 and the metal and polysilicon field plate structure 1014 can be implemented such they are in Schottky contact with the P junction extension region 704. Note that in an embodiment the Schottky contact basically has a barrier between the contact and the silicon, and that is with a depletion layer (not shown). In one embodiment, it is noted that the metal and polysilicon field plate structure 1014 includes the polysilicon field plate 810.

It is pointed out that in one embodiment, the adaptive charge balanced edge termination 1010 can include, but is not limited to, the P junction extension region 704, the field plate structures 1008, the metal and polysilicon field plate structure 1014, the polysilicon field plate 810, and the gate runner 806. In an embodiment, a layer of polyimide (not shown) can be deposited above and over the source metal 1004, metal 1002, the gate runner 806, the field plate structures 1008, the metal and polysilicon field plate structure 1014, and any other structures and upper surfaces of the semiconductor device 1000. In one embodiment, a passivation layer (not shown) can be deposited above and over the source metal 1004, metal 1002, the gate runner 806, the field plate structures 1008, the metal and polysilicon field plate structure 1014, and any other structures and upper surfaces of the semiconductor device 1000.

Within FIG. 10, it is understood that a greater or lesser number of field plate structures 1008 can be implemented within the adaptive charge balanced edge termination 1010 of the semiconductor device 1000 than the five field plate structures 1008 shown. For example, in various embodiments, the semiconductor device 1000 can be implemented with, but not limited to, a set of metal and polysilicon field plates 1014, a set of metal field plates 1008, and/or a set of polysilicon field plates 810. In one embodiment, the number of field plates structures 1008 implemented within the adaptive charge balanced edge termination 1010 of the semiconductor device 1000 can depend on the voltage of the semiconductor device 1000 and the physical limits of the lithography equipment being utilized to fabricate the semiconductor device 1000. In an embodiment, note that the minimum achievable distance between the metal contacts of the field plate structures 1008 can be related to the critical field of the silicon of the semiconductor device 1000. In various embodiments, the gap distance or size located between each of the field plate structures 1008 can be similar to other gap distances or can be different or can be a mixture of similar and different distances. For example in various embodiments, the gap distance or size between two field plate structures (e.g., 1008) can be implemented as 2 microns, 3 microns, or a few microns, but is not limited to such.

Note that an adaptive charge balanced edge termination (e.g., 106 or 1010) of a semiconductor device (e.g., 100 or 1000) can be fabricated or implemented in accordance with various embodiments of the invention.

It is pointed out that the adaptive charge balanced edge termination 1010 and the semiconductor device 1000 may not include all of the elements illustrated by FIG. 10. Moreover, the adaptive charge balanced edge termination 1010 and the semiconductor device 1000 can each be implemented to include one or more elements not illustrated by FIG. 10. Note that the adaptive charge balanced edge termination 1010 and the semiconductor device 1000 can be utilized or implemented in any manner similar to that described herein, but is not limited to such.

FIG. 11 is a flow diagram of a method 1100 for fabricating in accordance with various embodiments of the invention an adaptive charge balanced edge termination of a semiconductor device. Although specific operations are disclosed in FIG. 11, such operations are examples. The method 1100 may not include all of the operations illustrated by FIG. 11. Also, method 1100 may include various other operations and/or variations of the operations shown. Likewise, the sequence of the operations of flow diagram 1100 can be modified. It is appreciated that not all of the operations in flow diagram 1100 may be performed. In various embodiments, one or more of the operations of method 1100 can be controlled or managed by software, by firmware, by hardware or by any combination thereof, but is not limited to such. Method 1100 can include processes of embodiments of the invention which can be controlled or managed by a processor(s) and electrical components under the control of computer or computing device readable and executable instructions (or code). The computer or computing device readable and executable instructions (or code) may reside, for example, in data storage features such as computer or computing device usable volatile memory, computer or computing device usable non-volatile memory, and/or computer or computing device usable mass data storage. However, the computer or computing device readable and executable instructions (or code) may reside in any type of computer or computing device readable medium or memory.

At operation 1102 of FIG. 11, an epitaxial layer (e.g., 604) can be formed on or above a substrate (e.g., 602). It is noted that operation 1102 can be implemented in a wide variety of ways. For example, in one embodiment the substrate at operation 1102 can include a first dopant while the epitaxial layer can include a lower concentration of the first dopant. Operation 1102 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1104, a junction extension region (e.g., 704) for termination can be generated within an upper surface of the epitaxial layer. Note that operation 1104 can be implemented in a wide variety of ways. For example, in an embodiment the junction extension region for termination can include a second dopant. Operation 1104 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1106 of FIG. 11, a field dielectric (e.g., 706) can be formed and defined over or above the upper surface of the epitaxial layer. It is pointed out that operation 1106 can be implemented in a wide variety of ways. For example, operation 1106 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1108, gate dielectric (e.g., 802) can be formed and defined over or above field dielectric and/or the upper surface of the epitaxial layer. Note that operation 1108 can be implemented in a wide variety of ways. For example, operation 1108 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1110 of FIG. 11, a conductive material (e.g., 804) can be formed and defined over or above gate dielectric. It is noted that operation 1110 can be implemented in a wide variety of ways. For example, operation 1110 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1112, a dielectric layer (e.g., 904) can be formed over or above the conductive material, field dielectric, and/or the upper surface of the epitaxial layer. It is pointed out that operation 1112 can be implemented in a wide variety of ways. For example, operation 1112 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1114 of FIG. 11, one or more cavities or holes (e.g., 1012) can be formed through one or more of the dielectric layer, gate dielectric, field dielectric, and into the junction extension region for termination. Note that operation 1114 can be implemented in a wide variety of ways. For example, operation 1114 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1116, a field ring (e.g., 1006) can be generated within the junction extension region for termination in the bottom of the one or more cavities. It is noted that operation 1116 can be implemented in a wide variety of ways. For example, in one embodiment each contact region at operation 1116 can include a higher concentration of the second dopant. Operation 1116 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1118 of FIG. 11, a conductive layer (e.g., 1002) can be formed over or above the one or more cavities, any dielectric layer, any conductive material, any field dielectric, and/or the upper surface of the epitaxial layer. It is pointed out that operation 1118 can be implemented in a wide variety of ways. For example, operation 1118 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1120, one or more portions of the conductive layer can be removed such that the conductive layer within each of the one or more cavities does not physically contact conductive layer in another cavity. Note that operation 1120 can be implemented in a wide variety of ways. For example, operation 1120 can be implemented in any manner similar to that described herein, but is not limited to such.

At operation 1122 of FIG. 11, a passivation layer or a layer of polyimide can be formed over or above any conductive layer and/or the upper surface of the epitaxial layer. It is noted that operation 1122 can be implemented in a wide variety of ways. For example, operation 1122 can be implemented in any manner similar to that described herein, but is not limited to such. In this manner, an adaptive charge balanced edge termination of a semiconductor device can be fabricated in accordance with various embodiments of the invention.

The foregoing descriptions of various specific embodiments in accordance with the invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and many modifications and variations are possible in light of the above teaching. The invention is to be construed according to the Claims and their equivalents.

Claims

1. A method comprising:

generating a junction extension region within an upper surface of an epitaxial layer of a semiconductor device, wherein said epitaxial layer comprising a first type dopant and said junction extension region comprising a second type dopant;

generating a field ring within said junction extension region and comprising a higher concentration of said second type dopant than said junction extension region; and

forming a field plate above and in physical contact with said field ring, said field plate comprises a metal and a polysilicon that are both located above and extend beyond said junction extension region,

wherein an edge termination of said semiconductor device comprises said junction extension region, said field ring, and said field plate.

2. The method of claim 1, further comprising:

forming a plurality of metal field plates, said edge termination comprises said plurality of metal field plates.

3. The method of claim 1, further comprising:

forming a plurality of polysilicon field plates, said edge termination comprises said plurality of polysilicon field plates.

4. The method of claim 1, wherein said junction extension region comprises laterally varying doping of said second type dopant.

5. The method of claim 1, wherein said field plate is in ohmic contact with said junction extension region.

6. The method of claim 1, further comprising:

forming a tub region within said epitaxial layer and comprising said second type dopant.

7. The method of claim 1, further comprising:

generating a plurality of field rings within said junction extension region, each of said plurality of field rings comprising a higher concentration of said second type dopant than said junction extension region, said edge termination comprises said plurality of field rings.

8. A method comprising:

generating a junction extension region within an upper surface of an epitaxial layer of a metal oxide semiconductor field effect transistor (mosfet) device, wherein said epitaxial layer comprising a first type dopant and said junction extension region comprising a second type dopant;

generating a plurality of field rings within said junction extension region, each of said plurality of field rings comprising a higher concentration of said second type dopant than said junction extension region; and

forming a plurality of field plates, a field plate of said plurality of field plates is above and in physical contact with a field ring of said plurality of field rings, said field plate comprises a metal and a polysilicon that are both located above and extend beyond said junction extension region,

wherein an edge termination of said mosfet device comprises said junction extension region, said plurality of field rings, and said plurality of field plates.

9. The method of claim 8, wherein each of said plurality of field plates comprises metal.

10. The method of claim 8, wherein each of said plurality of field plates comprises polysilicon.

11. The method of claim 8, wherein said junction extension region comprises laterally varying doping of said second type dopant.

12. The method of claim 8, further comprising:

forming a tub region within said epitaxial layer and comprising said second type dopant.

13. The method of claim 12, wherein said tub region in contact with and laterally adjacent to said junction extension region and extends deeper than said junction extension region.

14. The method of claim 8, wherein a second field plate of said plurality of field plates is above and in physical contact with a second field ring of said plurality of field rings.

15. A method comprising:

generating a junction extension region within an upper surface of an epitaxial layer of a semiconductor device, wherein said epitaxial layer comprising a first type dopant and said junction extension region comprising a second type dopant, said junction extension region comprises laterally varying doping of said second type dopant;

forming a tub region within said epitaxial layer and comprising said second type dopant;

generating a field ring within said junction extension region and comprising a higher concentration of said second type dopant than said junction extension region; and

forming a field plate above and in physical contact with said field ring, said field plate comprises a metal and a polysilicon that are both located above and extend beyond said junction extension region,

wherein an edge termination of said semiconductor device comprises said junction extension region, said field ring, and said field plate.

16. The method of claim 15, further comprising:

forming a plurality of metal field plates, said edge termination comprises said plurality of metal field plates.

17. The method of claim 15, further comprising:

forming a plurality of polysilicon field plates, said edge termination comprises said plurality of polysilicon field plates.

18. The method of claim 15, wherein said field plate is in ohmic contact with said junction extension region.

19. The method of claim 15, further comprising:

forming a plurality of field rings within said junction extension region and each comprising a higher concentration of said second type dopant than said junction extension region.

20. The method of claim 15, wherein said tub region contacts said junction extension region and extends deeper than said junction extension region.